A turbojet comprises an air inlet at its upstream side supplying a fan and a compressor, the blades of which are supported on disks fixed to a shaft that extends over most of the turbojet, and that is driven in rotation by a turbine of the turbojet. Note that the terms “upstream” and “downstream” should be considered relative to a general direction of fluid flow through the turbojet, from the upstream side to the downstream side.
An intake cone is mounted at the upstream end of this shaft to deflect part of the air flow that enters inside the turbojet towards the fan blades, this flow then being separated into a core engine flow that flows into an inlet orifice to the compressor, and a fan flow that flows around the compressor and that is then mixed with the core engine flow and/or supplies turbojet component cooling circuits.
FIG. 1 diagrammatically shows such an intake cone 10. The axial attachment of the intake cone 10 on the shaft is generally made using screws inserted in attachment holes 11 located on the cone 10, for example there may be five of these holes. The cone 10 also comprises disassembly holes 12, conventionally there are three of these holes, for progressive extraction of the cone 10 along the axial direction.
Furthermore, the cone may perform a balancing function of the turbojet. The cone 10 is then provided with a plurality of holes for balancing screws 13 at a circumferential spacing from each other. For example, there may for example be twenty radial holes 13 provided on the cone, one for each fan blade. The turbojet can be balanced if the weights of the balancing screws are chosen judiciously.
The attachment holes 11, the disassembly holes 12 and the holes for the balancing screws 13 are all geometric discontinuities responsible for flow disturbances on the upstream side of the fan, and degrade the aerodynamics of the system.